In angiography, for visualization of vascular systems, radiopaque contrast media is injected into the vascular system and the outflow of contrast media is then documented under x-ray control. In this case naturally only information about the lumen of the vessel can be provided since the vessel wall is not contrasted by the contrast medium used. The advantage of angiography lies in its ability to provide high-quality information. In order to obtain further information about the structure of the vessel wall or structures adjacent to it, such as stents or other types of implants for example, other invasive technologies such as intravascular ultrasound (IVUS) or optical coherence tomography for example are needed. Additional physiological information is obtained using so-called pressure wire technology or intravasal Doppler wire technology.
The disadvantage of these technologies is that they frequently lack orientation in the vascular system. Spatial orientation is carried out indirectly using anatomical landmarks (such as plaques, outlets of side branches etc.). Another possibility is the use of magnetic navigation and positioning systems (GIVUS). In these systems the IVUS transducer can be equipped with a special sensor and then the position can be determined very precisely using a magnetic field generator. The disadvantage of this method is the high financial outlay for the navigation system and the additional equipping of the IVUS catheter with the position sensors, so that application for clinical routines is too costly.
Intravasal diagnostic methods are typically applied in such a way that an instrument such as a catheter or a Doppler/pressure wire is brought to the most distal position and is then withdrawn (automatically or manually) from this position. In such cases the examination data obtained is recorded digitally.